1. Field of the Invention
The present invention relates to a one-way clutch device which is assembled in a starter apparatus, or the like, for an automatic two-wheeled vehicle, and a method for manufacturing the same.
2. Related Background Art
A starter apparatus for an automobile is additionally provided with a one-way clutch device for performing torque transmission from an electric motor side to an internal combustion engine side only, in order to prevent overrun of the electric motor after the internal combustion engine is started. As a one-way clutch device of this type, one type is dominantly used in which clutch elements such as torque transmission rollers, cam surfaces and a spring is interposed between an inner race element and an outer race element, and these clutch elements are accommodated in and retained by a cage which is formed of a steel plate or synthetic resin (see the Japanese Utility Model Registration No. 2574315 (page 3, FIG. 1), the Japanese Patent Publication No. 56-41847 (page 3, FIG. 1), the Japanese Utility Model Publication No. 49-20603 (page 2, FIG. 6) and the Japanese Patent Application Laid-Open No. 11-117955 (page 1, FIG. 2, particularly), for example).
Also, there is disclosed in the Japanese Patent Application Laid-Open No. 11-117955 a one-way clutch device in which a cage formed of an elastically deformable material comprises a cylindrical portion and a flange, the flange has a plurality of clapper pieces which are elastically deformable and extended substantially in a circumferential direction, and the clapper pieces are inserted in flange receiving grooves formed on the outer race by the use of the elastic deformation of the clapper pieces to be fixed in the axial direction. That is, the flange is provided with a small-diameter portion and the clapper pieces which are extended substantially in the circumferential direction to be elastically deformable formed on the same flat surface thereof. On the outer race, there are formed flange receiving grooves each having the diameter larger than that of the small-diameter portion of the flange and smaller than that of the clapper piece. When each of the clapper pieces is flexed to be moved to the position of the flange receiving groove, the elastically deformable clapper piece is, with the property of returning into its original form, fitted into the flange receiving groove, whereby the one-way clutch is retained at that position in the axial direction.
The conventional one-way clutch device described above functions well without any trouble in a starter apparatus for a four-wheeled vehicle in which the maximum number of rotations of the internal combustion engine is comparatively low which is, e.g., approximately 6,000rpm . However, when this clutch device is used in a starter apparatus for an automatic two-wheeled vehicle in which the maximum number of rotations of the internal combustion engine is comparatively high which is, e.g., approximately 15,000 rpm, such a problem as described below may be brought about. That is, for example, during the operation of the internal combustion engine, a constituent member of the one-way clutch device is affected by the centrifugal force which follows the rotation. In the case of an automatic two-wheeled vehicle, the centrifugal force becomes very large due to the high maximum number of rotations, so that coupling columns of the cage are sometimes deformed to spread in the outer diameter direction. Moreover, since the centrifugal force acting on the spring becomes larger in the same manner, the spring may come off the cage such that its function of urging the torque transmission rollers can not be performed.
There is another fear that the cage and a member and the like assembled in the cage may fall out from the outer race member (outer race element) at the time of conveyance prior to the installation thereof to the main body of the two-wheeled vehicle, an automatic transmission, etc.,
In the one-way clutch disclosed in the Japanese Patent Application Laid-Open No. 11-117955, the elastically deformable clapper pieces are fitted into the flange receiving groove, with the property of returning into its original form, so that the one-way clutch is retained at that position in the axial direction. For this reason, it is possible to prevent fall out of parts such as a cage. However, the structure disclosed in the Japanese Patent Application Laid-Open No. 11-117955 mainly depends on the elastic deformation of the clapper pieces, which is not always advantageous to prevention of a fall out of the cage or the like parts.
Further, when the constituent parts of the cage are assembled to complete the cage, the assembling performance of each part is not always satisfactory. For example, when the detention piece is to be fitted in the recess, the detention may be hooked by the recess.